@th

Radium. The other three at least had uses, if the downsides were way more significant.

Lead makes paint a lot tougher, so you won't have to do maintenance as often.

Heroin does reduce pain, but I can't think of a more addictive painkiller off the top of my head.

Asbestos saved lives by preventing the spread of fires, but not as many lives as it killed.

Radium was just a fad with no benefits, just like so-called AI.